The first Heartland Institute conference on climate change in 2008 had all the trappings of a major scientific conclave – minus large numbers of real scientists. Hundreds of climate change contrarians, with a few academics among them, descended into the banquet rooms of a lavish Times Square hotel for what was purported to be a reasoned debate about climate change.

But as the latest Heartland climate conference opens in a Chicago hotel on Monday, the thinktank's claims to reasoned debate lie in shreds and its financial future remains uncertain.

Heartland's claims to "stay above the fray" of the climate wars was exploded by a billboard campaign earlier this month comparing climate change believers to the Unabomer Ted Kaczynski, and a document sting last February that revealed a plan to spread doubt among kindergarteners on the existence of climate change.

Along with the damage to its reputation, Heartland's financial future is also threatened by an exodus of corporate donors as well as key members of staff.

In a fiery blogpost on the Heartland website, the organisation's president Joseph Bast admitted Heartland's defectors were "abandoning us in this moment of need".

Over the last few weeks, Heartland has lost at least $825,000 in expected funds for 2012, or more than 35% of the funds its planned to raise from corporate donors, according to the campaign group Forecast the Facts, which is pushing companies to boycott the organisation.